1. Field of the Invention
The invention relates to image sensor technology and more particularly to a method for forming an image sensing device.
2. Description of the Related Art
An image sensor converts optical information into electrical signals. Charge coupled devices (CCD) and complementary metal oxide semiconductor CMOS image sensor devices are widely used in digital imaging applications. Recently, with continued advanced technological development, there has also been an increasing demand for highly-efficient image sensors in various fields such as digital cameras, camcorders, personal communication systems, game devices, surveillance cameras, micro-cameras for medical use, robots, and so on.
FIG. 1 shows a cross section to illustrate fabrication of a conventional lens package. In FIG. 1, a conventional lens 102 and a barrel 104 are assembled and the assembled device is then combined with a sensor holder 106 and an image sensing element 108. The conventional lens package is manually assembled. Thus, the cost is high and yield is low. FIG. 2 shows a cross section to illustrate fabrication of a conventional wafer level lens package. In FIG. 2, a glass spacer 206 is interposed between a wafer level lens 202 and an image sensing element 204. Focusing of the wafer level lens package device is performed according to thickness of the glass spacer 206. In order to fit various product specifications, a plurality of glass spacers 206 are required. However, the glass spacers are expensive and thus cost of the wafer level lens package is high.